Development of a viable biofuel replacement for petrochemicals poses at least three challenges. The first challenge is to identify a raw material that can produce biofuels completely compatible with engines currently run on petrochemicals without the need for conversion. The second challenge is to develop a cultivation technology that can produce this raw material at a competitive cost in the volume necessary to support the current demand of diesel, gasoline, and jet fuel consumers. The third challenge is to create a biofuel industry that can eliminate the negative environmental and economic impact of petrochemical energy use without creating a host of different but equally negative results, such as competition for food crops, competition for arable land, and creation of toxic byproducts. Sugar and/or starch crops, such as sugar cane, sugar beets, sweet sorghum and corn, to produce ethanol have been researched as a viable biofuel source. Opponents of currently exploratory fuels claim that, for example, corn ethanol production does not result in a net energy gain or that the consequences of large scale ethanol production to the food industry and environment offset any potential gains from ethanol. Plants that naturally produce oil, such as oil palm, soybean, algae, and jatropha, to produce biodiesel have also been explored.
Algaculture is a form of aquaculture involving the farming of species of algae. When cultivating algae, several factors must be considered, and different algae have different requirements. The water must be in a temperature range that will support the specific algal species being grown. Nutrients must be controlled so algae will not be “starved” and so that nutrients will not be wasted. Light must not be too strong nor too weak. Algae can be cultured in open-ponds or photo-bioreactors.
Open-ponds, as the name implies, are large, exposed bodies of water in which algae is grown. They are much more vulnerable to contamination by other microorganisms, such as invasive algal species or bacteria. Because of these factors, the number of species successfully cultivated in an open-pond system for a specific purpose is relatively limited. In open systems, one does not have control over water temperature and lighting conditions. The growing season is largely dependent on location and, aside from tropical areas, is limited to the warmer months.
Algae can also be grown in a photo-bioreactor (PBR). A PBR is a bioreactor which may incorporate some type of light source. Virtually any translucent container could be called a PBR, however the term is more commonly used to define a closed system, as opposed to an open tank or pond. Because these systems are closed, all essential nutrients must be introduced into the system to allow algae to grow and be cultivated. Essential nutrients include carbon dioxide, water, minerals and light. Some PBR's operate in a “batch mode” where a container (for example, a bag) is filled with water, inoculated with a small amount of algae, allowed to grow for a period of time supplemented with nutrients, then drained from the container for harvest of the entire culture. Other PBR's operate in a “continuous mode” where the container is actually an extended circuit through which the algae media is circulated indefinitely, supplemented with nutrients, and once the culture reaches optimal density, subsequent excess culture is diverted from the PBR to maintain PBR culture density. Algae may be diverted by a range of mechanisms; the most efficient mechanism being a continuous harvester incorporated into the circuit that extracts algae from the media without interrupting its continuous flow through the circuit. While a closed system that operates in continuous mode may yield more algae, if sufficient care is not taken, algae cultures in closed continuous bioreactors may collapse very quickly.
Various designs have been attempted to address some of these problems:
U.S. Patent Application No. 2010/0068779, published for Wells et al., is directed an algaculture system for the production of biofuels that includes a photo-bioreactor (PBR) including pump/tank assembly in communication with an input portion of a solar collector. The pump/tank assembly may act as a reservoir and/or agitator for a mixture of algae, water and nutrients which mixture may be pumped into the solar collector. The solar collector may comprise a plurality of interconnected tubes (in various configurations) with a plurality of axial vortex flow generators positioned at an intake portion of each tube. Sensors, ports for input of nutrients and gasses, and ports for removal of gasses may be located in fittings between sections of tubing. An output portion of the solar collector may be in fluid communication with a continuous harvester which may redirect mature algae for processing thereof.
U.S. Patent Application No. 2012/0214198, published for Trosch is directed to bioprocess engineering methods in which aqueous phases of anaerobic biologically treated organic suspensions are supplied to algal cultures as media components. The present invention also relates to the use of aqueous phases of anaerobic biologically treated organic suspensions as media components of algal cultures. Additionally, the present invention relates to the use of aqueous phases of anaerobic biologically treated organic suspensions to improve the growth conditions of algae in photobioreactors. Furthermore, the present invention relates to the use of algae for the treatment of aqueous phases of anaerobic biologically treated organic suspensions, in particular of anaerobic biologically treated sewage filtrate. The present invention also relates to bioprocess engineering devices comprising a bioreactor, in particular a fermentation tower and a photobioreactor.
U.S. Patent Application No. 2010/0255569, published for Camarate de Albuquerque Maranhao is directed to a closed transparent photobioreactor having a dome and a staged column wherein the dome is used as a growth chamber to provide a large culture volume to land area used and a flow pattern inside the dome allows for the uniform distribution of light energy, thereby negating growth rate inhibiting ‘dark zones’. A pump delivers culture from the bottom of the column to a lower portion of the dome and drives circulation between the two components and an increase in mass in the dome results in a spillover from the top of the dome into the column. Once in the column, algaculture will be aerated at each stage before returning to the dome. The staged column also provides for semi-continuous harvest of algae through the application of froth flotation and various other separation processes.
U.S. Patent Application No. 2013/0263501, published for Monroe is directed to a system and method for biomass fuel production and integrated biomass and biofuel production that includes a leaching system configured to receive biomass and rinse the biomass in an acidic solution such that water soluable combustion unfriendly chemical components in the biomass are leached into an effluent. The system may further include a torrefaction reactor configured to receive the biomass and heat the biomass to generate torrefied biomass.
U.S. Pat. No. 8,507,233, issued to Goel is directed to methods, systems, devices and materials for producing biofuels under nanoscale control (“nanobiofuels”) are provided. In one aspect, the invention provides method for producing a biofuel, including providing a hydrocarbon producing organism; exposing the biological hydrocarbon producing organism to conditions effective to cause substantial release of the hydrocarbon from the biological hydrocarbon producing organism; and isolating at least a portion of the hydrocarbon. At least one of the actions of providing, exposing, and isolating is performed using a corresponding nanoscale control.
It is an objective of the present invention to provide an Algaculture system that can provide fuels that can replace present day petrochemicals and be used in engines and machinery with a minimum of adjustment or modification. It is a further objective to provide such systems that can run continuously and economically on readily available algae strains. It is a still further objective of the invention to provide systems that will have a minimal adverse effect on the environment. It is yet a further objective to provide that can be easily operated and maintained. Finally, it is an objective of the present invention to provide systems that can operate with a variety of algae feed stocks.
While some of the objectives of the present invention are disclosed in the prior art, none of the inventions found include all of the requirements identified.